[v3,0/3] boost: Add Boost.Python NumPy

UPDATE[v3]: Updated Upstream-Status to Submitted [https://github.com/bfgroup/b2/pull/611]
UPDATE[v2]: I replaced the python-numpy-native trigger with a Boost b2
feature that skips the probing for NumPy if the numpy module's
include directory is supplied.

This was necessary as NumPy has a C extension which can't be safely
imported when cross-compiling.

----

The recipe for Boost does not support building Boost.Python NumPy.

There is a mistake in the variables supplied to test for numpy. A new
PACKAGECONFIG option is also provided to allow it to be optionally
enabled.

Below are the commit messages with additional debug information:

boost: Use python3-native executable

    The Boost build system executes Python in the compile task to
    import the Numpy module and print the include directory.

    We must specify the python3-native executable in the user-config.jam
    so that the python.jam can execute it properly.

    Without this change, it specifies a non-existant python executable
    and reports "No such file or directory" in log.do_compile.

```
$ grep -C4 "running" temp/log.do_compile
notice: [python-cfg]   interpreter command: "/ala-lpggp31/rwoolley/boost-fix/bitbake-builds/poky-master-poky-with-sstate-distro_poky-machine_qemuarm64/build/tmp/work/cortexa57-poky-linux/boost/1.91.0/recipe-sysroot/usr/bin/python3"
notice: [python-cfg]   include path: "/ala-lpggp31/rwoolley/boost-fix/bitbake-builds/poky-master-poky-with-sstate-distro_poky-machine_qemuarm64/build/tmp/work/cortexa57-poky-linux/boost/1.91.0/recipe-sysroot/usr/include/python3.14"
notice: [python-cfg]   library path: "/ala-lpggp31/rwoolley/boost-fix/bitbake-builds/poky-master-poky-with-sstate-distro_poky-machine_qemuarm64/build/tmp/work/cortexa57-poky-linux/boost/1.91.0/recipe-sysroot/usr/lib/python3.14"
notice: [python-cfg] Checking for NumPy...
notice: [python-cfg] running command '/ala-lpggp31/rwoolley/boost-fix/bitbake-builds/poky-master-poky-with-sstate-distro_poky-machine_qemuarm64/build/tmp/work/cortexa57-poky-linux/boost/1.91.0/recipe-sysroot/usr/bin/python3 -c "import sys; sys.stderr = sys.stdout; import numpy; print(numpy.get_include())"'
sh: line 1: /ala-lpggp31/rwoolley/boost-fix/bitbake-builds/poky-master-poky-with-sstate-distro_poky-machine_qemuarm64/build/tmp/work/cortexa57-poky-linux/boost/1.91.0/recipe-sysroot/usr/bin/python3: No such file or directory
notice: [python-cfg] NumPy disabled. Reason:
notice: [python-cfg]   /ala-lpggp31/rwoolley/boost-fix/bitbake-builds/poky-master-poky-with-sstate-distro_poky-machine_qemuarm64/build/tmp/work/cortexa57-poky-linux/boost/1.91.0/recipe-sysroot/usr/bin/python3 -c "import sys; sys.stderr = sys.stdout; import numpy; print(numpy.get_include())" aborted with
notice: [python-cfg]
```

boost-build-native: Add python-numpy-include feature

    The Boost python.jam file attempts to import the NumPy module to determine
    whether the Boost.Python NumPy extension should be enabled. This approach
    is problematic when cross-compiling, particularly when NumPy includes
    native extensions built for the target architecture.

    Introduce the new python-numpy-include feature to avoid probing for NumPy
    at build time by allowing the include path to be specified explicitly.

    This enables BitBake to provide the correct NumPy include directory from
    the recipe sysroot, eliminating the need to import the target NumPy
    module from site-packages.

boost: Add support for Boost.Python NumPy extension

    Support for NumPy was added to Boost release 1.63.

    This additional numpy PACKAGECONFIG ensures that python3-numpy
    is added as build-time and run-time dependencies. It uses the
    custom-made python-numpy-include feature to supply the directory
    for the numpy module headers to the b2 build system.

    If numpy is not added the PACKAGECONFIG it will still attempt the
    probe and fail gracefully like before.

With this support in place we may add a PACKAGECONFIG to enable numpy.

Shown here in conf/local.conf:
```
PACKAGECONFIG:append:pn-boost = " numpy"
```

$ grep python-cfg -A10 log.do_compile
notice: [python-cfg] Configuring python...
notice: [python-cfg]   user-specified version: "3.14"
notice: [python-cfg]   user-specified cmd-or-prefix: "/ala-lpggp31/rwoolley/boost-fix/bitbake-builds/poky-master/build/tmp/work/cortexa57-poky-linux/boost/1.91.0/recipe-sysroot-native/usr/bin/python3-native/python3"
notice: [python-cfg]   user-specified includes: "/ala-lpggp31/rwoolley/boost-fix/bitbake-builds/poky-master/build/tmp/work/cortexa57-poky-linux/boost/1.91.0/recipe-sysroot/usr/include/python3.14"
notice: [python-cfg]   user-specified libraries: "/ala-lpggp31/rwoolley/boost-fix/bitbake-builds/poky-master/build/tmp/work/cortexa57-poky-linux/boost/1.91.0/recipe-sysroot/usr/lib/python3.14"
notice: [python-cfg]   user-specified condition: "<python-numpy-include>/ala-lpggp31/rwoolley/boost-fix/bitbake-builds/poky-master/build/tmp/work/cortexa57-poky-linux/boost/1.91.0/recipe-sysroot/usr/lib/python3.14/site-packages/numpy/_core/include"
notice: [python-cfg] Details of this Python configuration:
notice: [python-cfg]   interpreter command: "/ala-lpggp31/rwoolley/boost-fix/bitbake-builds/poky-master/build/tmp/work/cortexa57-poky-linux/boost/1.91.0/recipe-sysroot-native/usr/bin/python3-native/python3"
notice: [python-cfg]   include path: "/ala-lpggp31/rwoolley/boost-fix/bitbake-builds/poky-master/build/tmp/work/cortexa57-poky-linux/boost/1.91.0/recipe-sysroot/usr/include/python3.14"
notice: [python-cfg]   library path: "/ala-lpggp31/rwoolley/boost-fix/bitbake-builds/poky-master/build/tmp/work/cortexa57-poky-linux/boost/1.91.0/recipe-sysroot/usr/lib/python3.14"
notice: [python-cfg] Checking for NumPy...
notice: [python-cfg] NumPy enabled
notice: Searching '.' for project-config configuration file 'project-config.jam'.
notice: Loading project-config configuration file 'project-config.jam' from '.'.
Performing configuration checks

    - default address-model    : 64-bit [1]
    - default architecture     : arm [1]

Building the Boost C++ Libraries.

$ find image \( -name libboost_py* -o -name libboost_nu* \) | xargs  ls -al
-rw-r--r-- 3 rwoolley users     3262 Aug 12 13:16 image/usr/lib/cmake/boost_numpy-1.91.0/libboost_numpy-variant-shared-py3.14.cmake
-rw-r--r-- 3 rwoolley users     3316 Aug 12 13:16 image/usr/lib/cmake/boost_numpy-1.91.0/libboost_numpy-variant-static-py3.14.cmake
-rw-r--r-- 3 rwoolley users     3280 Aug 12 13:16 image/usr/lib/cmake/boost_python-1.91.0/libboost_python-variant-shared-py3.14.cmake
-rw-r--r-- 3 rwoolley users     3334 Aug 12 13:16 image/usr/lib/cmake/boost_python-1.91.0/libboost_python-variant-static-py3.14.cmake
-rw-r--r-- 3 rwoolley users  1642060 Aug 12 13:15 image/usr/lib/libboost_numpy314.a
lrwxrwxrwx 1 rwoolley users       27 Aug 12 13:15 image/usr/lib/libboost_numpy314.so -> libboost_numpy314.so.1.91.0
-rwxr-xr-x 1 rwoolley users   702176 Aug 12 13:15 image/usr/lib/libboost_numpy314.so.1.91.0
-rw-r--r-- 3 rwoolley users 10658572 Aug 12 13:15 image/usr/lib/libboost_python314.a
lrwxrwxrwx 1 rwoolley users       28 Aug 12 13:15 image/usr/lib/libboost_python314.so -> libboost_python314.so.1.91.0
-rwxr-xr-x 1 rwoolley users  4727368 Aug 12 13:15 image/usr/lib/libboost_python314.so.1.91.0

Signed-off-by: Rob Woolley <rob.woolley@windriver.com>
---
Changes in v3:
- Updated Upstream-Status to Submitted [https://github.com/bfgroup/b2/pull/611]
- Link to v2: https://patch.msgid.link/20260812-fix-boost-v2-0-cbcb65f5e186@windriver.com

---
Rob Woolley (3):
      boost: Use python3-native executable
      boost-build-native: Add python-numpy-include feature
      boost: Add support for Boost.Python NumPy extension

 .../boost/boost-build-native_1.91.0.bb             |  3 +-
 .../add-python-numpy-include-feature.patch         | 74 ++++++++++++++++++++++
 meta/recipes-support/boost/boost.inc               |  9 ++-
 3 files changed, 84 insertions(+), 2 deletions(-)
---
base-commit: 96872cac87349528fa0516fa2f6265adf0a15dd7
change-id: 20260806-fix-boost-fca31915ebc4

Best regards,
--  
Rob Woolley <rob.woolley@windriver.com>